1. Field of the Invention
This invention relates to a method for making multi-layered shingles, and to roofing shingles made thereby. The shingles are uniquely thickened to enhance the appearance of a roof.
2. Description of the Prior Art
There have been many approaches by the roofing industry to the task of covering a roof deck with shingles which are both protective and aesthetically pleasing. Whatever their appearance, suitable shingles have been made sufficiently durable and weatherproof for prolonged protection of the roof. The shingles"" visual appeal has been attained in various ways, such as by providing particular butt edge contours and surface treatments which function to simulate more traditional, and in most cases more expensive, forms of roof coverings, including thatch, wooden shakes, slates, and even tiles of various forms.
Simulation of such more traditional roof coverings is afforded by asphalt shingles of the laminated type. These shingles provide depth or its appearance on the roof, thus more or less giving the look of the wood or other natural appearing shingles. U.S. Pat. No. 3,921,358 provides an example of such composite shingles. After describing the futile attempts in the past to achieve the irregular, bulky, butt edge profile and surface contour characteristic of wood roofing shingles, this patent presents an improved composite shingle comprising a rectangular sheet having a headlap portion and a butt portion. The butt portion is divided into a series of spaced apart tabs and a strip is secured to the sheet in a position underlying the tabs and filling the spaces therebetween. While the resultant bilaminate structure suggests somewhat the substantial and imposing architectural appearance of the more expensive roofing materials, such as wood shingles, the structure still diverges considerably in appearance from them.
For many years roofing manufacturers have offered a variety of two-layered shingles of the type disclosed in U.S. Pat. No 3,921,358 in the attempt to present a thicker and more attractive appearance. A structure markedly different from these prior art bilaminate shingles is shown in U.S. Pat. No. 4,869,942. This structure, which has an exposed butt portion three layers in depth, with tabs two layers in depth, and an additional strip under the cut-outs, gives the shingle an appearance that goes well beyond the bilaminates in simulating wood and tile shingles.
Although the asphalt composite shingles have significant cost, service life and non-flammability advantages over wood shingles, the latter type are still seen by many to be a much more desirable roofing material for aesthetic purposes. A key reason for wood shingles"" continuing aesthetic appeal stems from their greater thickness relative to the composite shingles, in spite of the many efforts in the past to simulate this thickness. Accordingly, it would be most beneficial to find ways to enhance the appearance of depth in the composite shingles without sacrificing these shingles"" advantageous features.
It is therefore an object of the invention to provide an asphalt shingle that simulates very closely the thickness of wood or other traditional roof coverings, and also possesses those attributes desired in roof coverings, including waterproofness, durability and fire-resistance.
It is a further object of the invention to enhance the appearance of a laminated shingle through the use of multiple layers of the butt portion of the shingle.
It is yet another object of the invention to provide a simple, efficient and economical manufacturing process for the continuous production of a laminated shingle from a single indefinitely long roofing sheet.
The foregoing and other objects of the invention have been achieved by a roof shingle which is multi-layered for enhancement of the shingle""s visual appeal and thickness. The composite shingle comprises a headlap portion and a butt portion having three or more layers. The headlap portion may also be multi-layered, comprising two or more layers. The butt portion is divided into a series of spaced apart tabs. The spacing between the tabs significantly exceeds that of the slots which have been formed over the years in the manufacture of multi-layered shingles, such as those disclosed in U.S. Pat. Nos. 5,209,802 and 5,426,902. Such narrow openings, which are typically less than one inch, e.g., about xc2xc to ⅝ inch, do not provide the openly spaced and particularly deep wells of a roof surfaced by the shingles of the present invention. The spacing between the tabs of the inventive shingles is greater than 1 inch, preferably greater than 2 inches.
The multi-layered shingle is of the laminated type. The butt portion of this shingle composite is made of at least three laminae, and may have four, five or more laminae. The laminae are preferably constructed of felted material comprising organic or inorganic fibers or a mixture of both. The fibers are usually held together with a binder and are coated, saturated, or otherwise impregnated with an asphaltic bituminous material. The laminae lie one above another in the composite, and are exposed to view as a bulky composite when the shingle is installed on a roof. Inherent in this laminated construction is an appreciable difference in surface elevation between the top surface of the tabs of one shingle and the top surface of the tabs of the underlying shingle(s). The perception of depth is greatly magnified when the array of shingles on the roof is viewed. The viewer""s eye will naturally go from the deep wells formed by the adjoining tabs of one shingle to those of the next upper or lower shingle(s) and so forth over the roof.
A preferred laminate manifesting the inventive shingle""s unique structure, incomparable to any of the prior art, comprises an asphalt shingle having a headlap portion and a butt portion which extends from the lower boundary of the headlap portion to the butt edge of the shingle and comprises a series of composite tabs which are separated by spaces, each extending from the side edge of one composite tab to that of the next adjacent composite tab, and each of which comprises at least three layers. The type of laminated shingle consisting of a single overlay member and a single underlay tab is well-known and illustrated, for example, in U.S. Pat. Nos. 3,998,685 and 5,052,162.
In accordance with the process of the invention, one or more fibrous sheets, which are to be made into the shingles, are treated with a cementitious waterproofing composition, such as asphalt or other bituminous material. The treatment includes surfacing the sheet or sheets; with sufficient waterproofing material to which is adhered granules such as crushed rock, slate or other surfacing material. While the entire outer face of the shingle, i.e. the face which is uppermost when the shingle lies on a roof, is desirably covered over its full extent with granular matter, the portion of the outer face which is important for colorful effects is that portion which is exposed to view when the shingles are laid together in overlapping courses on a roof. Accordingly, the sheet portions which ultimately become these exposed portions are profitably surfaced with colorful granules so as to provide areas of distinctive coloration, and lower cost, less decorative granular material is employed to surface the sheet portions which are to become the covered or hidden areas of the final assemblage.
The process is advantageously carried out continuously with the sheet(s) being transported along a production line for sequential processing. The continuous process is especially useful in the production of laminated shingles from a single elongate sheet. In the process, the top surface of the sheet is coated with asphalt and a coating of granules is applied to this surface. At least two narrow elongate sheets or strips are cut from the total elongate sheet to yield a main sheet and the narrow portions cut therefrom. The narrow elongate sheets are desirably cut from the main sheet in one step, although the cuts may be made in more than one step. The narrow sheets are positioned one above another and below the main sheet. A laminate of the main and narrow sheets is formed.
Desirably, each narrow sheet is coextensive with the other or others, and the narrow sheets are positioned so that the side edges of each one are in the same vertical plane as the respective side edges of the other(s) lying above and/or below. The first narrow sheet moved directly below the main sheet is centered on the longitudinal line which will become the central line of the multi-layered portion of the total composite sheet before cutting of this total sheet. Each succeeding narrow sheet is centered on the narrow one above it. After centering, each cut-off sheet is adhered to the sheet above it to form a composite. Each cut-off sheet may or may not be inverted before adhesion. In the formation of an advantageous embodiment, the last adhered sheet is inverted. When the bottom sheet is thus inverted, the final multi-layered tab portion of the resultant roofing shingle has exposed granules on both its top and bottom. The eventual shingle""s butt edge is thickened by the multiple layers and their protruding granules, leading to an assembly of the shingles on a roof which has the aesthetically attractive, bulky look of a roof of wood or tile shingles.
A longitudinal cut is made along the centerline of and within the side boundaries of the multi-layered portion of the totally laminated composite sheet advancing along the production line so as to form two complementary sheets, each individually having multi-layered tabs separated by cut-out portions along the thus cut longitudinal edge. The cut defines a substantially zigzag or xe2x80x9cdragons"" teethxe2x80x9d configuration comprising a series of interdigitated tabs on each complementary sheet. This side-edge arrangement is of the type described in U.S. Pat. No. 5,052,162. Each resulting composite sheet is cut transversely into shingles of preselected lengths. The zigzag cut desirably forms a series of tabs which differ from one another in each individual shingle so as to create a wooden shake simulation. The final shingle may thus be made from a single sheet, e.g., glass mat, by a process which converts this sheet into a plurality of shingles having multi-layered tabs, each layer being made of a portion of the original sheet. This multi-level roofing shingle is more visually appealing than previous bi-level shingles because of its thicker butt edge. This look of thickness is especially manifest when the shingles are arrayed in rows on a roof and the shingles of each row act like levers lifting the butt edges of the row above and so forth over the entire roof.
An important aspect of the present invention is that it permits laminated shingles having multi-layered tabs, such as those of three layers, to be manufactured continuously and expeditiously from a single sheet(s) of an indefinite length. Each of the steps involved in the formation of the final roofing shingles can be carried out on the base roofing material (e.g., glass fiber mat) as the material advances continuously along the production line in the form of an elongate sheet and strips cut therefrom. The continuously performed steps comprise waterproofing the sheet, coating it with mineral granules, cutting it along its length into elongate strips, laminating these strips together to form a composite multi-level strip, and finally cutting the composite laminated strip into the individual roofing shingles. The granules may be applied before or after the sheet is cut into elongate strips, as described, for example, in U.S. Pat. No. 4,869,942, and may be applied to only a portion of the main sheet or narrow strips. A different coloration may be applied to the main sheet and strips.
In a preferred embodiment of the invention, trilaminated shingles are continuously produced from a single elongate sheet which is waterproofed and coated over its top surface with mineral granules before being cut into elongate strips. Two first straight cuts divide the sheet into three elongate rectangular strips, one much wider than the other two. Advantageously, one of the straight cuts is made near one of the side edges of the original elongate sheet, and the other straight cut is made near the original sheet""s opposite side edge. One of the two narrow strips is shifted, without being inverted, to a position underneath the wide strip and the two strips are laminated together. Prior to lamination, the upper strip""s undersurface which is to be bonded is advantageously coated with an adhesive material. Additionally, in another embodiment, the lower strip is turned upside down before lamination so that the laminate of the two strips has the granules of the top strip facing upwardly and the granules of the bottom strip facing downwardly. The second narrow strip is shifted underneath and laminated to the bi-level portion formed in the first lamination. Preferably, the undersurface of the bi-level portion is coated with an adhesive and the second narrow strip is turned upside down before lamination so that the total composite will have granules on both the top and bottom of the three-layered, laminated section.
A third cut is made (i) alternately across and generally along the centerline of the tri-level section (i.e., multi-layered portion) formed by the two previous laminations and (ii) within the longitudinal side boundaries of this section. This central cut, which divides the sheet into two elongate parts, is made to form a repeating pattern of interdigitating triply thick tabs so that upon separation each part has a long straight edge along one side which is one layer in thickness and alternating triply layered tabs and cut-out portions along the other side. Each of the narrow strips, which were positioned to underlie the uppermost wider strip, is desirably cut to be wide enough to completely cover the underside of the wider strip""s tabs, but not so wide as to extend much toward the long straight edge of the wider strip. The width is desirably sufficient to adequately support the overlying shingle portion and to contribute to ease of production in the continuous manufacturing process. The two elongate laminated sheets are finally cut into suitable lengths for shingles and packaged. This final cutting may be accomplished conveniently just about when the third longitudinal cut is made or thereafter.
The continuous process thus provides a unique shingle structure having alternating tabs, three layers in depth and cut-outs therebetween. Like conventional bilaminates, this structure comprises a rectangular sheet having headlaps and butt portions. When these prior art and inventive laminated shingles are installed in successive offset courses in separate arrangements on a roof, their butt edge portions are exposed to view. Because the inventive trilaminated shingle""s butt portion is three layers in depth, with the tabs and cut-outs three layers deep, the shingle presents, through this unusual enlargement of the butt portion, a bulky appearance that very closely approaches that presented by wood and tile shingles.